Electricity meters are devices that measure and/or meter aspects of energy provided to a load. The load may be a residence, business, or even part of a larger electricity distribution system. Commonly available meters include electromechanical meters and electronic meters. Electromechanical meters employ a rotating disk that rotates in response to electric and magnetic fields induced by the electricity passing to the load. As is known in the art, the disk rotation speed is a function of the amount of electricity delivered to the load. Mechanical counters accumulate the number of disk rotations, which is indicative of energy consumed by the load. In some cases, an electromechanical meter can employ processing circuitry to perform additional operations with the consumption information provided by the rotating disk.
Electronic meters typically employ processing circuitry instead of the rotating disk and mechanical counters. In such meters, sensors within the meter detect the voltage and current that is delivered to the load. Circuitry within the meter converts the sensed voltage and current into digital values. Processing circuitry then employs digital signal processing to calculate consumed energy, among other things, from the digital values. Electronic meters provide greater flexibility in the types of energy consumption information that they may calculate, track, and store.
An electric meter that measures the electrical power flow through a power line typically uses a small portion of the electric power that flows through the line to provide electrical power to the circuits, processors, and other components within the electric meter itself. Of course, in some situations the flow of electricity to the electric meter is interrupted due to a power outage. Some simple electric meters, such as electromechanical disk meters, cease operation when the electric power supply is interrupted and resume operation upon restoration of electric power. However, more sophisticated electric meters generate measurements and billing data based on measurements of the electrical power over longer periods of time, and a loss of electrical power means that the electric meter loses a significant amount of data. More sophisticated prior art electric meters use a form of uninterruptable power supply (UPS) with an independent energy store such as a battery or large capacitors (sometimes referred to as “supercapacitors”) that enables the electric meter to either maintain operation during a short interruption in electrical power through the power line or, in the case of longer interruptions, to transmit information stored in the memory of the electric meter to an external monitoring system prior to exhaustion of the energy store in the UPS.
While prior-art UPS implementations reduce the likelihood of data loss in an electric meter due to unexpected losses of electrical power, these devices add to the cost and complexity of the electric meter while simultaneously increasing the electrical energy consumption of the electric meter and potentially reducing the reliability of the electric meter. In some situations, the potential for a failure of the battery or other component in the UPS can actually increase the likelihood that the electric meter will experience a failure and be unable to monitor an electric line, which is actually counterproductive since the underlying reason to include the UPS is to improve the reliability of the electric meter. Consequently, improvements to electric meters that mitigate the effects of power loss without requiring prior-art UPS implementations would be beneficial.